Chronoscope



Nov. 13, 1951 w. w. CUSHMAN CHRONOSCOPE Filed s t. 27, 1946 INVEN TOR.

4 TroRA/Ey Patented Nov. 13, 1951 UNITED STATES PATENT OFFICE 2,574,467 CHRONOSCOPE Walton w. Cushman, Webb City, Mo. Application September 27, 1946, Serial No. 699,651 14 Claims. (01. 161-15) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) The invention described herein, if patented, may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a chronoscope, and more particularly, to a chronoscope which is electrically operated and is especially designed to measure fractional seconds of time.

It is a major object of this invention to provide an improved chronoscope which is electrically operated and which accurately measures with a minimum margin of error periods of time less than that of a second and which chronoscope is especially adapted to measure the time required for a person to perform an act such as applying an automobile brake after a signal has been given. 7

It is another object of this invention to provide a device for measuring short periodsof time and having a dial and pointer, each rotatable in opposite directions in a step-by-step manner in synchronism with the electrical impulses of an alternating current source.

It is a further object of this invention to provide an improved chronosccpe having a dial and a pointer each rotatable alternately in opposite directions and each having separate coaxial ratchet wheels alternately driven by pawl mechanism mounted on an armature of an electromagnet.

It is still a further object of this invention to provide an improved device for measuring fractional seconds of time and having a dial and pointer alternately rotatable in opposite directions in synchronism with an alternating current source and in which the drive means includes an oscillating armature mounted on a leaf spring having. one end fixed and the other end free.

Still another object of this invention is to provide an improved chronoscope having a dial mounted on a hollow shaft and a pointer mounted on a solid shaft extending coaxially through the hollow shaft, in which the shafts are provided with ratchet wheels which arealternately driven step-by-step in opposite directions, and in which means are provided for manually returning the dial and pointer to zero setting.

Still a further object of this invention is to provide a reaction time indicator including alternating current circuit which may be closed and opened by switch means to fix the reaction time and in which electromagnetic means are included to convert the electrical impulses to mechanical impulses during the reaction time,

2 which mechanical impulses are registered on a dial.

Other objects and advantages of this invention will appear in the following detailed description and particularly will be pointed out in the appended claims, reference being had to the accompanying drawing forming a part of the specification, and in which:

Figure 1 is a front elevational view of the chronoscope of this invention and showing the dial and pointer;

Figure 2 is a longitudinal sectional view through the chronosccpe of this invention and showing the interior construction and with the electrical circuit being shown diagrarnatically;

Figure 3 is a transverse sectional View of a portion of the chronoscope taken on line 33 of Figure 2; and

Figure 4 is a detail elevational view of one of the ratchet whels.

Referring to the drawing, the numeral I refers generally to a case made of plastic or other suitable material and having a base member 2, front wall 3, rear wall 4, and a combined side and top wall 5 arched over the top of the case. The case is provided with a reinforcing bar 6 at the top interconnecting the front and rear walls 3 and 4, respectively. The base. front, and rear walls and top bar (5 may be molded as a unit and the combined side and top member 5 is preferably rernovably attached in any suitable mannear so that access can be had to the interior of the chronosco e for re air or other e. T e front wall 3 and the rear wall 4 are rovided with bearings I and 8, res ectively. the bearing 1 receivine a hollow. r tatab e. sh aft a n the bearing 8 receiving a solid, rotatable shaft I0, as clearly shown in Figure 2. Also, as shown in Figure 2, the shaft Ill extends coaxially through hollow shaft 9 and has suitably affixed thereto at its forward end the pointer I I. The hollow shaft 9 has suitably affixed thereto at its forward end the dial I2. From this construction, it is apparent that the hollow shaft 9 with its dial I2, and the solid shaft Ill with its pointer I I are independently freely mounted for rotation in the case I.

As shown in Figure l, the dial I2 is provided with thirty subdivisions and with ten main divisions, each hearing indicia reading in thousandths of a second. It is further to be noted that the total scale of the dial illustrated rep resents two hundred and fifty (25G) thousandths of a second or A of a second. The design of the chronoscope is such that the pointer I I is driven step-by-step in a clockwise direction, as viewed in Figure 1, while the dial I2 is alternately rotated step-by-step in a counterclockwise direction. Furthermore, the design is such that the increment of rotation of either the pointer or dial is equal to /2 of the smallest subdivision illustrated in Figure l, and since there are thirty subdivisions around the dial, sixty strokes are required before the pointer reaches the two hundred and fifty (250) thousandths mark on the dial. Thus in operation, the pointer moves division clockwise, then the dial moves /2 division counterclockwise, then the pointer moves an-' other division clockwise, and so on, so that after thirty strokes of the pointer and thirty strokes of the dial, or sixty strokes in all, the pointer l I will be pointing downwardly diametrically opposite from the position shown in Figure I and at that moment the 250 mark on the dial will coincide with the pointer in that position. The timing of the ,deviceris such that this will take place in of a second.

The driving and synchronizing mechanism will now be described. The hollow shaft 9 has suitably fixed thereto for rotation therewith a ratchet wheel 13, as shown in Figure 2, and similarly, the shaft has suitably fixed thereto for rotation therewith the ratchet M, coaxially positioned relative ratchet wheel it. Each of the ratchet wheels I3 and it is provided with a predetermined number of teeth uniformly spaced and accurately machined around the periphery of the wheel. Figure 4 illustrates ratchet wheel 13 with sixty teeth, spaced 6 apart, around the periphery of the wheel. This is the proper number of teethrequired for each of the wheels 13 and M for use with the second scale shown in Figure 1 when a 60-cycle source of current is used, as described hereinafter. In Figures 2 and 3, for purposes of clarity only, the pawls 25 and 21 are shown enlarged and the ratchet wheels l3 and M are shown with fewer than sixty teeth to clearly show the interaction of the parts. In actual construction, sixty teeth would be used.

The mechanism for driving the ratchet wheels l3 and I4 constitutes the alternating current circuit denoted generally by numeral l5 and shown diagrammatically in Figure 2, and including a conventional plug IS, a make switch H, a break switch [8, and a solenoid l9 housed within the casei Lamp 20 may be included in the circuit, if desired, to provide for a visual stimulus to indicate when the circuit is closed. The solenoid l9 forms part of an electromagnetic device including a fixed iron core l9 extending through the solenoid and an oscillatable armature 2!, clearly shown in Figure 3. ,The base 2 of the case has fixed thereto by suitable means such as the screws 22 a leaf spring 23 upstanding from the base. This leaf spring 23 has fixed thereto intermediate its length the armature 2i, which receives oscillations from the solenoid l9 in synchronism with the alternating current oscillations in the electrical circuit 15. Thus, if the plug I6 is plugged into a 60-cycle alternating current circuit, the armature 2| will be attracted towards the iron core I9 at each alternating current peak and will be released under the spring action of, the leaf spring 23 each time the alternating current passes from positive to negative and vice versa,-and thus for each cycle of the alternating current, there will be two complete cycles of the armature 2i. Thus since thereare, sixty cycles of current impulses per second, therewill be one hundred and twenty complete vibrations applied to the armature 2i and the leaf spring 23, or two hundred and forty strokes in both directions.

At the upper free end of leaf spring 23, there is fixed by welding, or other suitable means, a pair of sleeve-like housings 2 and 25, the housing 24 slidably receiving pawl 23 and the housing 25 slidably receiving pawl 2?, as shown in Figure 3. The pawls 26 and 21 are normally urged upwardly by the coil springs 28 and 29 positioned beneath the respective pawls within the respective housings. As shown in Figures 2 and 3, pawl 26 is adapted to engage ratchet wheel Hi, and pawl 2? is adapted to engage ratchet wheel {3, and preferably the contacting forward face of each of the pawls is flattened where it contacts the ratchet teeth to provide for a sub stantial engaging surface. The housings 2 3 and 25 are illustrated as being fixed, one on each side of the leaf spring 23, but it is within the purview of this invention to fix both housings on the same side of the leaf spring, if desired.

As can be seen in Figure 3, when the armature 2| and spring 23 are attracted by the solenoidlfl' and moved to the right, the pawl 2? will drive ratchet wheel l3 counterclockwise one increment,- that is, the distance equal to the spacing between two adjacent ratchet teeth. This in turn will drive dial l2 counterclockwise of the smallest subdivision shown in Figure 1, or 6. Then when the solenoid i9 is deenergized, the spring 23 will be released towards the left and the pawl 25 will drive ratchet wheel Hi clockwise, which in turn will drive the pointer ll /2 of the smallest subdivision illustrated in Figure l, or 6, in a clockwise direction. Thus it can be seen that on each stroke of leaf spring 23 to or from solenoid it, one of the ratchet wheels will be driven an increment of 6, and since there are two hundred and forty strokes per second of the armature 2i and spring 23, or thirty strokes in each direction per sec ond, the dial and pointer will each move inopposite directions or a total of 360 in n of a second. Thus, it can be seen that a chronoscope has been provided in synchronism with an alternating current source in which there is pro vided a dial and pointer, both of which are adapted to move in opposite directions at 6 intervals in synchronism with the alternating current oscillations.

Although the dial illustrated and the chronic scope described is adapted for readings up to /s of a second, it is within the purview of this in vention to utilize chronoscopes having greater or lesser capacities, as for example, of a second or of a second 'or other capacities. For ex ample, if the capacity of the chronoscope is to be of a second it would merely be necessary to design the chronoscope so that each increment of movement would be 3 instead of 6, thus, requiring twice as long for the pointer H to reach the end of the scale. To obtain a 3 increment, it is merely necessary to utilize one hundred and twenty ratchet teeth on each of the ratchet wheels 13 and it; instead of sixty. Also in the second chronoscope, it would be necessary to shorten the length of the stroke of the spring 23 and armature 2 I, which can be accomplished in a manner well known in the electrical art.

It is further within the purview of this inven tion to utilize a current source other than the 50- cycle current, if desired. Thus for example, if a l20-cycle current source is used, there would have to be one hundred and twenty teeth in eaclr. ratchet wheel to maintain the A second scale.

In "such embodiment, the pointer and dial would each move sixty times to complete the scale.

The upper surfaces of the pawls 25 and 2? are beveled so that when pawl 26 is driving ratchet wheel I4, the pawl 27 will ride freely in a bachward direction without affecting pawl it, and vice versa. In order to prevent the ratchet wheels 13 and M from moving in a backward direction, stationary pawls 3E! and 3| are fixed to the bar 6 for engaging the ratchets i3 and 1%, respectively, to prevent their backward motion. These pawls 30 and 3% will not interfere with forward counterclockwise motion of ratchet wheel 13 and forward clockwise motion of ratchet wheel M.

In order to enable the manual return of the dial I 2 and pointer H to initial zero position, shown in Figure 1, after the chronoscope has been used, the rear end of shaft 19 is knurled as at $2 for manual turning of the shaft iii and the pointer l l in a forward direction until the pointer ll points directly upwardly. Similarly the crystal bezel 33, threaded as at as or otherwise affixed to the dial i2, is provided with a knurled periphery 35 so that the dial I2 may likewise be manually rotated forwardly to its zero position, shown in Figure 1. Also, the knurling 32 and provide a ready means whereby the zero setting may be adjusted when the pointer it does not fall exactly on the 259 mark.

In operation of the chronoscope, the stroke of leaf spring 23 is adjusted so that each pawl will move a distance greater than the distance between two adja'cent teeth but less than the distance between two alternate teeth, This adjustment will insure that the ratchetwheel will be driven the proper increment on each stroke. the increment being the length of a tooth or 6 in the particular chronoscope illustrated. Though the movement of the pawl will probably be somewhat greater than 6, this extra movement will be taken up by lost motion between the pawl and the ratchet wheel. Before using the chronoscope, it is necessary to set the pointer and dial at zero with one of the pawls in position for driving its ratchet wheel.

In using the chronoscope as a reaction indicator, as for example, when determining the reaction time of an individual in apolving the brakes of an automobile, the make switch I? can be closed to close the circuit I and start the pointer I! and dial 12 in motion. Simultaneously the lamp 29 will light giving an immediate signal to an individual that the o eration has commenced. The individual will then withdraw his foot from the accelerator and apply the brakes as fast as he can. As soon as the brake is a lied, the break switch !8 will open the circuit 15 and stop motion of pointer H and dial 52. At this moment, the pointer and dial will register the reaction time of the particular individual from the time the lamp 29 was energized until the brakes were applied. This chronoscope can also be used for other purposes wherein short intervals of time are to be measured.

Though the hollow shaft 9 is shown mounting the dial i2 and the solid shaft is is shown mounting the pointer H, the shafts may be reversed within the scope of this invention with the hollow shaft mounting the pointer and the solid shaft mounting the dial. In this construction, the dial could be positioned in front of the pointer and be transparent for viewing the pointer.

While the invention has been described in more or less detail, it is not to be limited there- 6 by, as changes may be made in the form, arrangement and construction of parts, and equivalents may be substituted, without departing from the spirit and scope of the invention as claimed, the forms hereinbefore described being merely preferred embodiments thereof.

I claim:

1. A device for measuring short intervals of time comprising a dial, a pointer associated with said dial, means for converting electrical impulses to mechanical strokes, and means for utilizing said mechanical strokes to impart stepby-step rotation to said dial and pointer, re spectively, in opposite directions.

'2. A device for measuring short intervals of time comprising a dial, a pointer associated with said dial, means for converting electrical impulses to mechanical strokes, and means for utilizing said mechanical strokes to impart step-by-step rotation to said dial and pointer, respectively, in opposite *directions, said firstmentioned means comprising a solenoid, a spring-mounted armature, and a pair of pawls.

3. A device for measuring short intervals of time comprising a dial; a pointer associated with said dial; means for converting electrical ii pulses to mechanical strokes; and means for utilizing said mechanical strokes to impart stepby-step rotation to said dial and pointer, respectively, in opposite directions; said first-mentioned means comprising a solenoid, a spring mounted armature, and a pair of pawls;- said secondmentioned means comprising a ratchet for opcrating said pointer and another ratchet for opcrating said dial; and each of said pawls being constructed and arranged to drive one of said ratchets.

4. A chronoscope comprising a dial, a pointer associated with said dial, a pair of shafts for mounting said dial and pointer, respectively, for rotation, and means for rotating said shafts in opposite directions in timed synchronism, one of said shafts being hollow and the other of said shafts extending coaxially through said hollow shaft.

5. A chronoscope comprising a dial, a pointer associated with said dial, a pair of shafts for mounting said dial and pointer, respectively, for rotation, and means for rotating said shafts in opposite directions in timed synchronism, one of said shafts being hollow and the other of said shafts extending coaxially through said hollow shaft, and said means comprising a ratchet wheel fixed to each of said shafts and a pawl for driving each ratchet wheel step-by-step.

6. A chronoscope comprising a dial, a pointer associated with said dial, a pair of shafts for mounting said dial and pointer, respectively, for rotation, and means for rotating said shafts in opposite directions in timed synchronism, said means comprising pawl and ratchet mechanism for each of said shafts and electromagnetic means for operating said mechanism in synchronism with electrical impulses.

7. A chronoscope comprising a rotatable dial, a rotatable pointer associated with said dial, a ratchet for driving said dial, another ratchet for driving said pointer, a pair of pawls for operating said ratchets in opposite directions, a solenoid, a spring-mounted armature associated with said solenoid, and mountings on said armature for said pawls.

8. A chronoscope comprising a rotatable dial, a rotatable pointer associated with said dial a ratchet for driving said dial, another ratchet for driving said pointer, a pair of pawls for operating said ratchets in opposite directions, a solenoid, a spring-mounted armature associated with said solenoid, and a mounting on said armature for said pawls, said mounting providing spring means for yieldingly urging said pawls against said ratchets.

9. A chronoscope comprising a rotatable dial, a rotatable pointer associated with said dial, means for driving said dial and pointer, respectively, step-by-step in opposite directions, and electromagnetic means for operating said first-mentioned means in synchronism with a source of alternating current.

10. A chronoscope comprising a rotatable dial, a rotatable pointer associated with said dial, means for driving said dial and pointer, respectively, step-by-step in opposite directions, and electromagnetic means for operating said first-V mentioned means in synchronism with a source of alternating current, said electromagnetic means including an armature formed of a leaf spring having one end fixed and the other end free, and said first-mentioned means comprising pawl mechanism mounted on the free end of said leaf spring.

11. A device for measuring short intervals of time comprising a rotatable dial, a rotatable pointer associated with said dial, means for alternately rotating said dial and pointer, respectively, step-by-step in oppositedirections, and means adapted to facilitate manual return of the dial and pointer to zero setting after operation.

12. A device for measuring short intervals of time comprising a rotatable dial, a rotatable pointer associated with said dial, means for rotating said dial and pointer, respectively, stepby-step in opposite directions, and means adapted to adjust the zero setting of said dial and pointer, respectively.

13. A device for measuring short intervals of time comprising a rotatable dial, a pointer associated with said dial, and a pair of shafts for mounting said dial and pointer, respectively, for rotation in opposite directions, said dial having a knurled periphery accessible for manual setting of said dial relative said pointer.

14. A reaction time indicator comprising an alternating current circuit, a solenoid in said circuit, make and break switch means in said circuit for closing and opening said circuit to determine the reaction time, an armature associated with said solenoid and adapted to oscillate in synchronism with the current oscillations in said circuit, a leaf spring mounting said armature and adapted to oscillate therewith, said leaf spring having one end fixed and the other end free, pawl mechanism mounted on the free end of said spring for movement therewith, ratchet means intermittently driven by said pawl mechanism, and dial and pointer means alternately operated in opposite directions by said ratchet means for indicating extent of movement of said ratchet means as a measure of the reaction time.

WALT W. CUSHMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 47,315 McGill 1 Apr. 18, 1865 291,745 Kubec Jan. 8, 1884 349,878 Garcia Sept. 28, 1886 2,166,153 Huck July 18, 1939 2,209,108 Briggs July 23, 1940 FOREIGN PATENTS Number Country Date 668,790 France July 22, 1929 

